Silver palladium electrodes

Electronic Applications. The PGMs have a number of important and diverse appHcations in the electronics industry (30). The most widely used are palladium and mthenium. Palladium or palladium—silver thick-film pastes are used in multilayer ceramic capacitors and conductor inks for hybrid integrated circuits (qv). In multilayer ceramic capacitors, the termination electrodes are silver or a silver-rich Pd—Ag alloy. The internal electrodes use a palladium-rich Pd—Ag alloy. Palladium salts are increasingly used to plate edge connectors and lead frames of semiconductors (qv), as a cost-effective alternative to gold. In 1994, 45% of total mthenium demand was for use in mthenium oxide resistor pastes (see Electrical connectors). 

H. Connor, Hydrogen diffusion through silver-palladium foil electrodes. Platinum Met. Rev., 1966, 10(4), 127. 

In palladium-silver alloys, larger amounts of hydrogen can be solubilised because the metal lattice has already been expanded by the silver atoms, and thus it is less brittle than the pure Pd lattice. Based on these considerations, the ideal silver content of the Pd cathode is between 20 wt% and 30 wt%. In order to obtain high flow rates of pure hydrogen, the maximum permeability of the Pd-Ag cathode must be realized. The hydrogen permeability P through the lattice of the Pd-Ag tubular electrode follows Sieverts law. The H2 permeating flow rate Qp (mol s ) can be derived from Equation [16.2] ... 

Sawyer DT, Day RJ (1963) Kinetics for oxygen reduction at platinum, palladium and silver electrodes. Electrochim Acta 8 589-594... 

Since the reaction between hydrogen and oxygen is very slow at room temperature, catalysts are incorporated in the carbon electrodes. At the anode, suitable catalysts are finely divided into platinum or palladium at the cathode, cobaltous oxide, or silver. The two halfreactions shown above yield the overall result as ... 

Just a few years after the discovery of the deposition and electroactivity of Prussian blue, other metal hexacyanoferrates were deposited on various electrode surfaces. However, except for ruthenium and osmium, the electroplating of the metal or its anodizing was required for the deposition of nickel [14], copper [15,16], and silver [9] hexacyanoferrates. Later studies have shown the possibilities of the synthesis of nickel, cobalt, indium hexacyanoferrates similar to the deposition of Prussian blue [17-19], as well as palladium [20-22], zinc [23, 24], lanthanum [25-27], vanadium [28], silver [29], and thallium [30] hexacyanoferrates. 

A series of pubKcations was devoted to the electrocatalytic reduction of nitrate by the Eindhoven group [50-54]. On the basis of these works, a comparative study was performed to determine the reactivity of nitrate ions in 0.1 mol dm concentration on eight different polycrystaUine electrodes (platinum, palladium, rhodium, ruthenium, iridium, copper, silver, and gold) in acidic solution using cyclic voltammetry, chronoamperometry, and differential electrochemical mass spectroscopy (DEMS) [50]. 

Electro-conductive rubber material Because of its great strength and much lower price than such expensive metals as silver and palladium, nano copper or copper-silver double metal powder can be used in the electronics industry to take the place of those expensive metals for the preparation of electro-conductive rubbers [191], electro-conductive slurry, and electrode materials etc. in addition, the copper-silver double metal powder has the characteristic of antibiosis. For such use nano copper or copper-silver powder should be needle-like crystalline the nano copper powders of sphere-like crystalline has very low electro-conductivity. 

The inks for screen-printing the electrodes contain the sub-micron metal powder, either a Ag-Pd alloy or a base metal, usually nickel (melting point, 1455°C) but sometimes copper (melting point 1084°C). Palladium (melting point, 1554°C) and silver (melting point, 961 °C) form solid solutions with melting points approximately proportional to the content of the end members. 

With reductions in ceramic sintering temperature, the cost of electrodes has been reduced by the use of Ag-Pd alloys, typically 70at.% Ag/30at.% Pd. The reduction in palladium content is limited to about 15 at.% because at lower levels silver migration becomes a problem. The drive to lower cost has led to efforts to avoid it entirely. One approach is based upon the injected or fugitive electrode (see Section 5.4.3 and Fig. 5.12) and the other on the use of the base metals nickel or copper for the electrodes (BME) combined with dielectrics resistant to the reduction firing necessary to retain the electrodes in the metallic state. 

Between 1980 and about 2000 most of the studies on the electrodeposition in ionic liquids were performed in the first generation of ionic liquids, formerly called room-temperature molten salts or ambient temperature molten salts . These liquids are comparatively easy to synthesize from AICI3 and organic halides such as Tethyl-3-methylimidazolium chloride. Aluminum can be quite easily be electrode-posited in these liquids as well as many relatively noble elements such as silver, copper, palladium and others. Furthermore, technically important alloys such as Al-Mg, Al-Cr and others can be made by electrochemical means. The major disadvantage of these liquids is their extreme sensitivity to moisture which requires handling under a controlled inert gas atmosphere. Furthermore, A1 is relatively noble so that silicon, tantalum, lithium and other reactive elements cannot be deposited without A1 codeposition. Section 4.1 gives an introduction to electrodeposition in these first generation ionic liquids. 

It has been shown that electroactive polymer films on electrodes can mediate electron transfer for metal deposition (9-11). Haushalter and Krause (5) have described the treatment of PMDA-ODA films with highly reactive Zintl complexes (e.g., Sn9 4, SnTe4 4) to yield an intercalated material able to reduce ions of platinum, palladium and silver at the film surface. Mazur et al., (12) reported the deposition of conductive Ag, Cu, and Au metal interlayers within a PMDA-ODA film by electrochemical reduction. 

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